In the die packaging technical field, a substrate is used for a die to be assembled thereon. A substrate usually comprises a build-up and a solder resist layer disposed on the build-up. The existing pattern of solder resist layer on a build-up of a substrate is a form of continuous flat plate. FIG. 1 shows an existing substrate 100 in which the pattern of the solder resist layer 101 on build-up 102 is a continuous flat plate. However, this kind of solder resist pattern layer has the several shortcomings. For example, thermal expansion mismatch between the die and substrate materials induces high stress, and the continuous flat plate type pattern of solder resist layer is not beneficial to reduce the stress accumulated on large solder resist area and relieve the stress induced by material coefficient of thermal expansion (CTE) mismatch of the substrate, which causes it to be easier to render warpage of the substrate or package. In addition, this pattern of the solder resist layer in the existing art is not beneficial to reduce die crack risk induced by die-substrate CTE mismatch.
Therefore, it is desirable to provide an improved stress relief pattern of substrate solder resist to eliminate or relieve the above shortcomings in existing art.